The overall goal of this project is to establish toxic skeletal fluoride threshold and to assess skeletal status following treatment withdrawal in osteoporotic patients undergoing therapy with intermittentent slow-release sodium fluoride and continuous calcium citrate supplementation. This project will test the hypothesis that this slow-release form of fluoride treatment with continuous calcium citrate supplementation would permit an improved skeletal tolerance of fluoride and that the beneficial skeletal effect of this treatment would be sustained following withdrawal of therapy.